1. Field of the Invention
The present invention generally relates to a liquid crystal display device, and more particularly relates to a thin film transistor array substrate and repair method thereof for a liquid crystal display device.
2. Description of the Prior Art
Currently, the thin film transistor liquid crystal display (TFT LCD) is the most popular plane display device. It has many advantages such as its low consumption, thin and compact shape, and low driving voltage, etc. Generally, a TFT LCD panel has a liquid crystal layer sandwiched by two substrates with electrodes thereof. Applying voltages to respect electrodes can control the light transmittance of the liquid crystal. The display region of a TFT panel is composed of a plurality of matrix-like pixels.
During the procedures of fabricating the TFT panel, the pixel is liable to be damaged and resulted in an abnormal short-circuit or open-circuit by several factors such as the static electricity and the unexpected particle pollution. The pixel defects can be distinguished as several kinds such as the white defect, the black defect, and the gray defect, etc.
FIG. 1 illustrates a partial plan view of the pixel structure for the liquid crystal display device according to the prior art. Referring to FIG. 1, the pixel structure is arranged a first metal layer 130 floating under a second metal layer 120 that is connected with a conductive pixel electrode 110. The second metal layer 120 is overlapped with the data line 140 and electrically insulated with each other. While the TFT is non-acting, the repair method is to irradiate the laser beam to electrically short at two laser repair regions “A”. However, this pixel structure requires an extra floating metal so as to cause decreasing the aperture ratio of the pixel. Further, because the voltage level is not constant, the voltage signal on the data line will influence the voltage of the pixel so as to cause the poor display quality. Besides, because of the accumulation of electrostatic charges, the overlapping region of the first metal layer and the second metal layer is easily damaged because of the electrostatic accumulation and the short between different metal in the same layer so as to increase the defective rate. This kind of laser repair structure needs to irradiate two laser beams to achieve the pixel repair. After repairing, the pixel is only presented the gray defect because of the average voltage of data line, so the gray defect can be found out under the black screen of the panel.
The laser repair structure above-mentioned needs to irradiate two laser beams. It is complicated and needs more repair time and cost. Hence, how to overcome the mentioned problem is important for enhancing the product yield and cost of the LCD device.